The present invention relates to a sterile-filtration filter for suspensions.
For filtration of sterile suspensions in the pharmaceutical domain, it is absolutely necessary that all parts of a filtration device be thoroughly cleaned mechanically prior to actual sterilization, e.g., by superheated steam, to remove any adhering solids. In general, this can only be accomplished by disassembling all of the individual parts of the apparatus. In many cases, disassembling the parts of a filter unit is possible, if at all, only at great expense.
A filter device with a plurality of filter candles which are arranged so as to be suspended in a pressure vessel is known. The retaining part of the two-part filter candles on the filtrate side is substantially formed by a tube carrying the actual filtering medium in the form of a woven hose. In the known device, the filter elements are arranged one after the other so as to be suspended at removable collecting tubes through which the clear filtrate is removed (EP-A-0 070 589). A filter device of this type is well-suited in large-scale chemical operations for washing out filter cakes or suspensions, but is not suited for sterile filtration in pharmaceutical applications.
EP-A-0 066 921 discloses a filter element which is formed by a closed central tube as supporting member and serves to remove a filtrate, filtering media being arranged around the tube. Either plastic tubes or metal tubes can be used.